Don’t be fooled by all the rain and snow this winter. Historically, another drought is likely around the corner. As “Water & Power: A California Heist,” a National Geographic documentary, airing Tuesday, makes clear, the state is facing problems that go deeper than filling its reservoirs.

The documentary from Marina Zenovich (“Roman Polanski: Wanted and Desired”) and executive produced by Academy Award winner Alex Gibney digs into the complicated questions of California’s water rights and the powerful interests that have controlled them.

Oddly, “Water & Power” likes to evoke Polanski’s 1974 “Chinatown.” The film noir fictionally incorporated the story of the state’s first great water scandal, in which the Los Angeles Department of Water and Power made a deal for Owens River water at the urging of some powerful forces in the city. Meanwhile, spigots were turned off to the farmers in the San Fernando Valley, forcing them to sell their land cheaply to the same big interests who had championed the deal.

Once most of the land was bought up, water was turned back on and the San Fernando Valley boomed, enriching inside investors. The documentary investigates more recent deals that could have dire affects on California’s long-term water health.

The documentary follows a number of journalists and activists to report out the story. One of its focuses is on the “Monterey Amendments,” a deal struck in 1994 that included the privatization of a critical underground reservoir. The result was that the Kern Water Bank was controlled by a single corporation and brought cheap water to farms run by billionaires Stewart and Lynda Resnick, who made a fortune on water-intensive crops like almonds, pistachios and pomegranates.

Shockingly, as profits soared for many megafarmers like the Resnicks, many local residents only had access to expensive and nearly undrinkable water. Worse, as the drought has gone on, California’s aquifers — natural underground water reserves — have been pumped to dangerously low levels. Because they are often so deep, rains do not as easily fill them as they would a reservoir.

It might be helpful to remember a more recent movie — “The Big Short.” At the end of that film, it was noted that one of the investors who foresaw the financial meltdown of 2008 was now investing in water. Why not? It is becoming more precious than oil.

And that is exactly what appears to be happening now in California. Since the law allows for any property owner to tap into the water below them, investors are buying up properties over aquifers. That gives them the right to drain an aquifer even if it goes under their neighbor’s land.

As water becomes more precious, the documentary raises the possibility that a few major for-profit companies will control something Californians consider a right.

“You’re going to be next,” warns a state resident who has been without water. “Water & Power: A California Heist” — part of a series of Nat Geo documentaries about the world’s water crisis — offers a very troubling picture, although it sometimes unpacks the information in confusing ways.

For instance, it rolls out the “Chinatown” reference too many times. Yes, we get it that bad things happened in the past and history can repeat itself, but what is really important is what has happened in the past three decades.

In one bit of good news, we are told at the end that there are steps being taken to address California’s ongoing water shortage, but the fear is that they are being rolled out too slowly. Still, you want to be informed about this and this doc can help.

Rob Lowman began at the L.A. Daily News working in editing positions on the news side, including working on Page 1 the day the L.A. Riots began in 1992. In 1993, he made the move to features, and in 1995 became the Entertainment Editor for 15 years. He returned to writing full time in 2010. Throughout his career he has interviewed a wide range of celebrities in the arts. The list includes the likes of Denzel Washington and Clint Eastwood to Kristin Stewart and Emma Stone in Hollywood; classical figures like Yo Yo Ma and Gustavo Dudamel to pop stars like Norah Jones, Milly Cyrus and Madonna; and authors such as Joseph Heller, John Irving and Lee Child. Rob has covered theater, dance and the fine arts as well as reviewing film, TV and stage. He has also covered award shows and written news stories related to the entertainment business. A longtime resident of Santa Clarita, Rob is still working on his first more-than-30-year marriage, has three grown children (all with master's degrees) and five guitars.